Retroviruses form a sub-group of RNA viruses which, in order to replicate, must first reverse transcribe the RNA of their genome into DNA ("transcription" conventionally describes the synthesis of RNA from DNA). Once in the form of DNA, the viral genome is incorporated into the host cell genome, allowing it to take full advantage of the host cell's transcription/translation machinery for the purpose of replication. Once incorporated, the viral DNA is virtually indistinguishable from the host's DNA and, in this state, the virus may persist for as long as the cell lives.
A particular species of retrovirus has been isolated from patients who suffer from Acquired Immune Deficiency Syndrome (AIDS) and has been given the designation Human Immuno Deficiency Virus (HIV). This retrovirus will infect and destroy cells expressing the CD.sup.4 marker and will preferentially infect and contribute to the destruction of human T-lymphocytes, commonly referred to as T-cells, bearing this marker which are involved in the functioning of the immune system. The patient progressively loses this set of T-cells, upsetting the overall balance of the immune system, reducing the patient's ability to combat other infections, and predisposing the patient to opportunistic infections which frequently prove fatal.
There are at least three clinical manifestations of HIV infection. In the initial "carrier" state, the only indication of infection is either the presence of HIV antibodies in the blood-stream or the ability to culture the virus. The next stage is known as `AIDS related complex` (ARC) and the physical symptoms associated therewith may include persistent general lymphadenopathy, general malaise, increased temperature and chronic infections. This condition usually progresses to the final, fatal AIDS condition, when the patient loses the ability to fight infection.
A particularly troublesome problem associated with combatting the HIV retrovirus is that the RNA to DNA reverse transcription process is fraught with repeated mutation which makes it extremely difficult for the body's immune system to recognize and attack infected cells along with the virus itself.
It is therefore, an object of this invention to provide a treatment for patients infected with a retrovirus, particularly the HIV retrovirus. It is a further object of the invention to enhance the body's ability to recognize and attack T-cells which are infected with the HIV retrovirus.
It is also an object of the invention to increase the number of T-cells in patients infected with HIV who have low numbers of T-cells due to the HIV infection and the patient's accompanying immunologic response.
A still further object of the invention is to provide a vaccine against infection by a retrovirus, particularly the HIV retrovirus.
Other objects of the invention will be apparent from the description of the invention which follows.